This invention relates to methods of testing and/or methods of selection and/or methods of manufacture applicable to the provision of vision aids for use in optical recognition tasks including reading. A particular aspect of the invention relates to the provision of vision aids to assist in reducing the effects of dyslexia and related and other optical disorders. It is to be understood that the term vision aids includes the use of a vision aid in which the aid is provided by the use of particular calorimetric parameters in the colour of the background of a visual display unit screen.
The invention provides a new approach to the selection and/or manufacture of tinted transparent vision aids for such use.
There is disclosed in U.S. Pat. No. 4,961,640 (Irlen) a system intended for the provision of tinted spectacles which are to be worn by the user at all times during which the intended benefits are requiredxe2x80x94see column 12 at lines 21 to 23. In the system of the U.S. 640 specification the tinted spectacle elements are selected (albeit with reference to graphic data relating to the optical parameters of the spectacle elements) on the basis of data obtained by purely intuitive methods based upon the patients""own interpretation of criteria selected (see the case studies commencing at column 7 and line 30). Case 1 refers to Ann, a woman of age 21 having very detailed listed perceptual impairments. It is stated at column 8, line 1 that Ann was then diagnosed with the IVPS test attached in xe2x80x9cAppendix 1xe2x80x9d, on which she scored 62% affirmative responses. The U.S. 640 specification does not include an xe2x80x9cAppendix 1xe2x80x9d so there is no disclosure relating to this test. However, it appears from the text in column 8 that this test is purely a diagnostic test related to the diagnosis of the perceptual impairments mentioned above. It is stated that clear glass lenses having no vision correction other than their tint and optical density, taken from the lens set specified in xe2x80x9ctable 1 abovexe2x80x9d were superimposed in a lens frame . . . The pages of the U.S. 640 specification likewise do not include a xe2x80x9ctablexe2x80x9d so it is difficult to know what this disclosure means. However, what is clear is what is stated (at column 8 at line 8) that xe2x80x9cin the case of Anne it appeared that the symptoms stated above were minimised by superimposition for both eyes of lenses pink 2 and green 1xe2x80x9d. It is then stated that Anne was given a conventional opthalmological examination and that (column 8, line 18) when fitted with the pink and green tinted lenses the patient reported a dramatic improvement in depth perception with clear peripheral vision. Other improvements are also noted including increased reading rate and the elimination of eye strain.
It needs to be clearly understood that the disclosure in the U.S. 640 specification in relation to Case 1 (Anne), case 2 (Betty), and Case 3 (Clio) entirely adopts the same intuitive approach to the identification of the calorimetric parameter applicable to the tinted spectacles to be used for improving vision. Thus, it is stated (column 8 at line 8) that xe2x80x9cin the case of Ann it appeared that the symptoms described above were minimised by superimposition for both eyes of lenses pink 2 and green 1xe2x80x9d. In other words, the tester just guessed which were the right lenses, tried them, and asked the patient how she perceived the result. The same applies to Betty and Clio. Likewise, there is no recognition in the U.S. 640 specification of the importance (or even the existence) of xe2x80x9ccolour spacexe2x80x9d. By colour space we mean (in one aspect of the invention in which the concept may be identified as xe2x80x9cperceived colour spacexe2x80x9d) the three-dimensional concept of the three calorimetric parameters which any tinted transparent vision aid possesses, namely values with respect to hue (or frequency) and saturation (or density) and luminosity (or total light energy).
In relation to hue (or frequency) the calorimetric parameters may alternatively be identified as. xe2x80x9cbiological/physical colour spacexe2x80x9d based on values on red/green/blue scales which thus provide an alternative definition of colour space. This latter approach (red/green/blue or R/G/B values are of particular relevance in relation to the testing and use of the method of the invention in relation to VDU screens.
Additionally, the U.S. 640 specification does not recognise the significance of types of optical tasks to be undertaken by the patient being tested.
While it is not disputed that the techniques disclosed in the Irlen specification can produce worthwhile benefits in terms of enhanced interpretation of visual data, we have discovered that the benefits available from the use of tinted screen devices (whether used as overlays placed on printed text, or used in relation to VDU screens as background colour or as a front-mounted screen tint element, or even in spectacle elements) are enhanced to an extent which is generally thought somewhat unlikely when the calorimetric parameters relating to the tinted elements are determined on a quantitative basis and applied to the selection or production of the optimum tinted element for a given patient. Indeed, our data suggest that far from the perhaps expected situation of diminishing returns for increasing accuracy in screen tint selection, in fact the opposite is true and the returns for such accuracy are far from diminishing and actually disproportionate to the numerical value of the three values in colour space (as discussed elsewhere as between an ill-matched screen tint and a well-matched one.
We have also discovered that not only are quantitative tests beneficial to an unexpected extent, but also that it is most important to separate the types of optical tasks to be undertaken by the patient into array tasks (such as reading or recognising rows of data, and non-array tasks such as the searching for and eventual finding of one or more hidden items on a page of data. We have thus discovered that the difference between array and non-array includes substantial differences in the use of the muscles of the eye which leads to fundamental differences in the optical problems associated with these two types of tasks. If the two types of tasks are confused or mixed as in the prior art such as the U.S. 640 specification, the results of the tests are, we have discovered, relatively low in value.
Finally, we have also discovered that in the methods of testing applicable to the provision of tinted transparent vision aids, the provision of an optimum such aid for a given patient requires attention to the three-dimensional aspects of the calorimetric parameters, namely the three-dimensionally plotable values of hue or frequency and saturation or density and luminosity or total light energy. Unless these three values of perceived colour space (or the red/green/blue or R/G/B values of biological/physical colour space, see discussion above) are taken in to account, the calorimetric parameters of the vision aid resulting from a testing procedure can only be, at best, a very rough approximation to the optimum values needed by the patient. There is no recognition in the U.S. 640 specification of this requirement nor of the distinction between array and non-array tasks.
An object of the present invention is to provide methods of selecting and/or making and/or using vision aid devices providing improvements in relation to one or more of the matters discussed herein or improvements generally.
According to the inventor there is provided a method and apparatus as claimed.
In an embodiment of the invention the method for quantitative determination of the calorimetric parameters (in three-dimensional colour space) of the tinted screen device, which in the embodiment forms the visual aid device, comprises monitoring the response of the patient to systematic test procedures on a numerical basis and recording the resultant test data on a graphical basis. The graphically recorded data is then available for interpretation with respect to the optimum values of the calorimetric parameters, and the next step in the method is to make such an evaluation whereby a relatively modest number of numerical data values can permit the relatively exact determination of the optimum value of the relevant parameter for the patient in question. We have discovered that the presently-available optimum indicator for quantitative determination of the calorimetric parameters is Rate of Reading (RR) in accordance with a systematised procedure for such RR determination. Alternatively, eye movements may be monitored and quantified during standardised tasks such as reading or another array task. Likewise, the method of the invention is also applicable to non-array tasks and quantitative and/or numerical data may be obtained for example on the basis of the time taken to find a hidden element within an area of data and/or a quantitative measure of eye movements occurring per unit time while carrying out such a task.
Thus, the other indicators which are considered also suitable as the basis for the quantitative determination step of the embodiments of the present invention include indices of eye movement during certain standardised procedures such as reading (or any other array task) or (but not both) non-array tasks, whereby these eye movement data indices provide numerical measures of the patient""s reaction to the use of a sequence of graduated (in three-dimensional colour space) calorimetric visual aid test elements such as tinted filters of screens, or tinted background colours in VDU screens etc.
The embodiments of the invention take as their starting point for the improvements provided by the invention the fact that the proposals of the prior art simply rely upon the intuitive interpretation of technical improvements in tinted screen amelioration of optical condition symptoms and see no basis (or perhaps no need) for determining these matters quantitatively regardless of the improvements which might thereby be available. By the discovery that the adoption of the inverse route (not involving assessment by the patient at all and basing itself on externally determinable data), the embodiments of the invention provide a new approach to the calorimetric determination of screen and other visual aid data by a hitherto unexplored route which surprisingly gives unexpectedly beneficial results. Likewise, the prior art includes no appreciation of the nature and the need for separation of array and non-array optical tasks, nor apparently any appreciation of the significance of the use of all three parameters of colour space. By separating array and non-array tasks and by testing with respect to all three-dimensions of colour space and performing these tests on a quantitative basis, the present invention embodiments provide significant improvements.
A particular aspect of the embodiments of the present invention relates to the interpretation and use of the test data obtained in, for example, the Rate of Reading test and/or the occular movements test. It is particularly significant that the embodiments of the present invention do not rely on self-assessment or an intuitive approach to the quantitative interpretation of the test results at all. Such is the province of the prior proposals and of the starting point for the tests carried out in the method of the present invention. The embodiments of the present invention obtain quantitative data by means of simple and reliable observational steps which are not open to subjective interpretational errors. Thus, whereas in the methods of the prior art, subjective assessment of the benefit obtained with a given hue or tint of test spectacle element on the part of the patient is required with, doubtless, an answer on the lines of: xe2x80x9cyes, quite goodxe2x80x9d or xe2x80x9cno, not very goodxe2x80x9d. In contrast, the embodiments of the present invention take the numerical data obtained during the test procedure by counting rate of reading in terms of words per unit time (and such counting may be automated by a suitable programmed computer system), or else the numerical value attributable to eye movements per unit time in accordance with a standardised test protocol, and uses these values as a quantitative expression of the benefit value of the vision aid under test. What is more, the embodiments of the present invention do not rely upon just selecting the particular one of the test elements which provides a better result than the others, but by means of analysis or interpretation of the numerical or other quantitative data the embodiments enable the selection of that particular value (in relation to three-dimensional colour space), which (by use of a short series of test results,) can be seen to correspond to the optimum result. In this connection, where the results are interpreted by a graphic technique or the like, the use of template data from a data bank of previous patients""test results enables informed interpretation of the test data (with respect to all three colorimetric parameters) for a particular patient to be carried out. In other words, although the profile of the plot of (for example) reading rate against the calorimetric parameters will vary from patient to patient, there is an underlying plot general profile which can be used to assist interpretation.
In the embodiments the three calorimetric parameters of the vision aids relate either to hue and saturation and luminosity and can be recorded (for any given vision aid) by a point in perceived three-dimensional colour space, or the corresponding R/G/B values in biological/physical colour space. These variables represent the parameters for providing vision aids which enable the matching of vision aid variables to the corresponding personal variables in relation to patients suffering from visually-related disorders such as dyslexia (in relation to array tasks) and the related disorder (in relation to non-array tasks), and the symptomatic alleviation of these difficulties and related ones.
The method of the invention may be practised in various ways including the use of the method as a means for identifying the point in colour space corresponding to the optimum requirements of a given patient. It is then merely a practical question as to whether this set of three parameters is simply selected from an array of closely spaced (in terms of the three variables) xe2x80x9ctinted screens/vision aids, or whether there is then set in motion a step to produce such a vision aid using the three parametric values and appropriate manufacturing techniques. There is available a manufacturing apparatus for such tinted screens which is capable of producing same relatively quickly on demand once the required parameter values have been identified. The present invention applies both to the mere selection of such tinted screens or filters and to their manufacture and indeed to the provision of other means for applying the identified calorimetric parameters to a patient""s eyes, such as by causing a vdu screen to be appropriately coloured.
It is to be understood that a particularly important embodiment of the present invention relates to the provision of a vision aid in the form of a vdu screen adapted to provide, as the screen background to the text or other graphics displayed on the screen, a colour having a quantitatively-determined set of calorimetric parameters these having been determined by optical tests (usually in relation to the screen itself), as a result of which the user""s ability to interpret data displayed against the background colour on the screen is maximised. The colorimetric parameters in relation to this aspect of the invention may comprise the basic three-dimensional perceived colour space parameters of hue, luminosity and density or may comprise the relevant red/green/blue or R/G/B values in relation to biological/physical colour space. In an embodiment described below relating to the use of the invention in relation to vdu screens, in addition to the R/G/B values being determined quantitatively, the technique also permits the related luminosity values likewise to be determined and/or optimised by means of quantitative tests.